By default, groups will retain their current group scope when they are migrated. You have the option to change that here, so that you can transform a group's scope as it is migrated. For example, if the new target does not have multiple domains, you may choose to convert your Universal Groups into Domain Local groups. Or you can choose not to migrate a particular group scope at all. There are some limitations on changing the scope of nested groups, so you may want to refer to the following TechNet link.
By default, your mail-enabled groups will retain their current group scope when they are migrated. You have the option to change that here, so that you can transform a group's scope as it is migrated. You can also change the group to a contact, or you can choose not to migrate a particular group scope at all.
If you choose skip, Directory Sync Pro for Active Directory will not make an association between those objects, and an error will be noted in the log file.
If you choose Merge, Directory Sync Pro for Active Directory will consider those items the same. This means that any members of the source group will be added to the membership list of the target group, if you have set updates to occur. No new object will be created.
With Rename, a new Active Directory group object will be created in the target. You will need to distinguish this from the matched target object by giving it a new name. You can manually add a prefix or suffix of your choice, or, you choose any existing AD attribute to be prepended or appended to the name. Remember that if you choose rename, when you update the object in the source such as adding another member, it will be the Renamed group object in the target that gets updated during a synchronization.
If "Synchronize Members as Foreign Security Principals" is enabled, group members that cannot be matched in the target will be synchronized as Foreign Security Principals if trust relationships allow it and the target group is a Domain Local Security Group.